This paper is devoted to modern approaches to development of new positioning algorithms which will guarantee the achievement of the minimum mean square error and do not create excessive computing load. The algorithm performing the search of global extremum in problems of source position estimation using one-step methods based on a likelihood function for two types of passive radar systems was proposed. The first system is a passive radar system consisting of narrow-base subsystems; the second system is the combined passive radar system which includes several narrow-base subsystems together with a wide-base passive radar system.
According to results of computer simulation, the analysis of the frequency of appearing abnormal errors and relative time spent on calculations was made. The comparison performed using the proposed algorithm with an adaptive step and a universal method of global extremum searching, that is “particle swarm”, showed that the developed algorithm requires up to 20 times less computational costs and vanishes abnormal errors.
The aim of this work is to develop an algorithm and program for calculating the dispersion characteristics of the resonator slow-wave systems with channel –flight filled with plasma, using the methods of three-dimensional modeling. To achieve this goal the following problems were solved: 1. the problem of describing the cell resonator slow-wave system with channel-flight filled with plasma transfer multipole matrix is formed and the ratio for determination the dynamic characteristics of slow-wave systems of the coefficients of the matrix are shown; 2. a review of methods for solving key problems of electrodynamics and programs suitable for determining the coefficients of the transfer matrix multipole modeling cell slow-wave system are given;
3. algorithm and data processing of software simulation of three-dimensional resonator slow-wave system are developed;
4. an analysis of the dispersion characteristics of the resonator slow-wave systems when the concentration of plasma is fulfilled.м
The procedure of measurements and the formulas for calculating the sample's reflection (R) and transmission (T) coefficients with the use of a passive terahertz spectrometer are presented. The passive spectrometer comprises of cold and room-temperature chambers interconnected via a multimode waveguide (light pipe). Spectral selective liquid helium-cooled detector is placed at the cold side, and a specular disk shutter is positioned near the room-temperature end of the light pipe. The metered coefficients R and T can be calculated as a result of the two consecutive synchronous detection measurements — with the specimen placed before and after the shutter. Passive terahertz spectrometry based on the selective cooled detectors is a good alternative to active one when the use of a sophisticated teraherz radiation source is difficult or undesirable.
Nonlinear Ginzburg-Landau equation for dirty supercondicting 1D wire is derived in the limit of high magnetic field.
We investigate contribution to the detectivity of superconducting radiation sensors, originated from a change in spectral functions of the absorber under influence of the absorbed power. For the absorber manufactured of dirty superconducting film we demonstrate that at low temperature the only cause of the change in spectral functions is the change of the order parameter. A method for calculation corrections to the spectral functions for the case of dirty film is suggested.
Abstract. The properties of slow-wave system (SWS) type of coupled cavity system with different slots connection are studied. The possibility of such SWS in the second bandwidth and increase of the operating frequency of the TWT, while maintaining the size of the SWS are shown.
Periodical electrodynamic structures are widely used to create powerful electronic devices, microwave filters, antennas. A wider class of heterogeneous media and slow-wave systems (SWS) is a pseudoperiodic structure proposed for the selection of waves, including the suppression or amplification of backward waves. These are, for example, synchronous helix (Solntsev Spiral-SS), including as a special case of a logarithmic spiral, with the suppression of pseudoperiodic waveguides parasitic backward waves. The principle of constructing pseudoperiodic-layered media is similar to the principle of creating pseudoperiodic waveguides and based on a consistent change in the thickness of the media’s layers along with the change of electric permittivity and magnetic permittivity, determining the phase shift of the electromagnetic field on the layer. According to this principle, the distribution pitch of the layers and the phase of the field along the structure are selected so as to maintain the phase velocity and amplitude of the selected spatial harmonics of the field the same as in the original periodic layered media and the amplitude of the other spatial harmonics decrease; selection takes spatial harmonics (spatial selection). In the pseudoperiodic-layered media expected to get a selection of backward spatial harmonics, which is the production of media with a backward wave having the opposite direction of propagation phase and energy flow. Investigation of the properties of electromagnetic waves in pseudoperiodic-layered media and slow-wave systems opens the possibility of creating on this basis new microwave devices. Media with a backward wave in recent years attracted the attention of many researchers, because they have new unusual laws of reflection and refraction and allow to obtain focus over beams in the microwave and optical ranges. The well-known works are "metamedia" based on the use of periodic electrodynamic structures (photonic or electromagnetic crystals). This paper presents a method and a program for calculating the properties of electromagnetic waves in a pseudoperiodic-layered media. Also some possibilities of allocation of backward waves in an environment that determine the properties of propagation of electromagnetic waves are shown.
In this paper we present a new type of cryogenic filter. This filter based on Fabry-Perot interferometer. We use quartz substrate covered by gold grid with low transmission coefficient. Thickness of quartz is 240 um and thickness of gold is 300 nm. The modeling of this filter was done in CST Studio. Filter was tested in room temperature. Backward wave oscillator was used like GHz source and pyroelectric was used like detector. For the cryogenic experiments was used black body (NiCr film on sapphire substrate). Cold-electron bolometer was used for signal detection. This filter can be inserted into cryostat and can be tuned mechanically. Q-factor is 25 and transmission 50% at frequency range from 100 GHz till 500 GHz were observed.
The formalized approach for periodic distortion analysis is presented. The computational method is based on exploitation of the properties of the simplified Newton iterative process to solve nonlinear problems in functional space. The numerical scheme of periodic distortion analysis is described. Unlike Volterra series this technique doesn’t require computation of the second and third derivatives of device models. The special-purpose mode for the periodic distortion analysis of RF circuits is based on the simulation in the frequency domain in the framework of the harmonic balance method.
Opal matrixes represent the regular 3D-pack of spherical particles of amorphous SiO2, forming an ordered system of voids. Opal matrixes with spherical particles of SiO2 diameter d ≈ 260 nm (Δd ≈ 2%) were synthesized. Nanocomposites were formed by filling voids (occupying ~26% of the volume) of opal matrixes by salt solutions, low-temperature heat treatment at 625–825 K and annealing at 975–1475 K. The formation in the voids of opal matrixes, depending on synthesis conditions, of the synthesized substances, SiO2 and products of interaction synthesized substances with SiO2 are submitted. The frequency dependences of the conductivity, real and imaginary components of the dielectric and magnetic permeability of nanocomposites containing crystallites 16–65 nm in size of magnetic materials — double phosphates (LiNiPO4, LiCoPO4) and vanadates (GdVO4 and DyVO4) were measured. The dielectric losses of nanocomposites remain low (at a level of ~0.06) in the frequency range 107–1010 Hz for nanocomposites with DyVO4 and LiCoPO4. The dielectric loss increases both in the direction of low frequencies (<106 Hz) and in the direction of THz frequencies. Investigations have demonstrated that the measured parameters are influenced by the phase composition, as well as the structural and magnetic state of the synthesized substances.